Cultivation of microalgae in dairy farm wastewater without sterilization

The present study investigated the feasibility of cultivating microalgae in dairy farm wastewater. The growth of microalgae and the removal rate of the nutrient from the wastewater were examined. The wastewater was diluted 20, 10 and 5 times before applied to cultivate microalgae. A 5 dilution yielded 0.86 g/L dry weight in 6 days with a relative growth rate of 0.28 d(-1), the 10×dilution gave 0.74 g/L and a relative growth rate of 0.26 d(-1) while the 20×dilution 0.59 g/L and a relative growth rate 0.23 d(-1). The nutrients in the wastewater could be removed effectively in different diluted dairy wastewater. The greatest dilution (20×) showed the removal rates: ammonia, 99.26%; P, 89.92%; COD, 84.18%. A 10×dilution removal% was: ammonia 93; P 91 and COD 88. The 5× dilution removal% was: ammonia 83; P 92; COD 90.